为什么远程上传到FTP时需要生成一个临时文件？

Question

I am so confused with this, I am trying to upload data to FTP through VBS script and it works fine for a single file file but doesn't upload multiple files when I add the script inside a loop.

Also , why do we need to generate a temporary file when remote uploading to FTP,

I mean to say this,

this is the script I am using,

Dim fso, folder, files, strPath
Set fso = CreateObject("Scripting.FileSystemObject")

strPath = "E:/Test"
Set folder = fso.GetFolder(strPath)
Set files = folder.Files

Const hostname = "ftp.domain.com"
Const port = 21
Const username = "username"
Const password = "password"
Const remoteDir =  "/"
Const useDefaultsExclusively = True
Const skipConfirmation = True


For each item In files

    If InStr(1, item.Name, "txt") <> 0 Then
    defaultFile = item.Name
    localFile = fso.getFileName(defaultFile)
    localDir = fso.getParentFolderName(defaultFile)
    Set shell = CreateObject("WScript.Shell")

  tempDir = shell.ExpandEnvironmentStrings("%TEMP%")
  ' temporary script file supplied to Windows FTP client
  scriptFile = tempDir & "\" & fso.GetTempName
  ' temporary file to store standard output from Windows FTP client
  outputFile = tempDir & "\" & fso.GetTempName

  'input script
  script = script & "lcd " & """" & localDir & """" & vbCRLF
  script = script & "open " & hostname & " " & port & vbCRLF
  script = script & "user " & username & vbCRLF
  script = script & password & vbCRLF
  script = script & "cd " & """" & remoteDir & """" & vbCRLF
  script = script & "binary" & vbCRLF
  script = script & "prompt n" & vbCRLF
  script = script & "put " & """" & localFile & """" & vbCRLF
  script = script & "quit" & vbCRLF


  Set textFile = fso.CreateTextFile(scriptFile, True)
  textFile.WriteLine(script)



  ' bWaitOnReturn set to TRUE - indicating script should wait for the program
  ' to finish executing before continuing to the next statement
  shell.Run "%comspec% /c FTP -n -s:" & scriptFile & " > " & outputFile, 0, TRUE
  Wscript.Sleep 10
  ' open standard output temp file read only, failing if not present
  Set textFile = fso.OpenTextFile(outputFile, 1, 0, -2)
  results = textFile.ReadAll
  textFile.Close

End If

Next

 fso.DeleteFile(scriptFile)
 fso.DeleteFile(outputFile)

Why do we creating a Temporary file with this code, :S

Set shell = CreateObject("WScript.Shell")

  tempDir = shell.ExpandEnvironmentStrings("%TEMP%")
  ' temporary script file supplied to Windows FTP client
  scriptFile = tempDir & "\" & fso.GetTempName
  ' temporary file to store standard output from Windows FTP client
  outputFile = tempDir & "\" & fso.GetTempName


 Set textFile = fso.CreateTextFile(scriptFile, True)
      textFile.WriteLine(script)



      ' bWaitOnReturn set to TRUE - indicating script should wait for the program
      ' to finish executing before continuing to the next statement
      shell.Run "%comspec% /c FTP -n -s:" & scriptFile & " > " & outputFile, 0, TRUE
      Wscript.Sleep 10
      ' open standard output temp file read only, failing if not present
      Set textFile = fso.OpenTextFile(outputFile, 1, 0, -2)
      results = textFile.ReadAll
      textFile.Close

Although I am looping through the script , it must upload every txt file inside current directory but it uploads only the first one, why is it so ?

When I print the current file ie

MsgBox defaultfile

it display the name of each txt file inside the current folder but uploads first file only.

Answer 1

There is no native method of live automation for FTP. This is actually a scripting workaround. Your script is creating a text file with FTP instructions. Then, it launches FTP from the command line using the -s switch. That -s switch allows you to provide a text file containing session commands for FTP.exe to execute before closing. So while your script isn't actually automating the FTP program directly, it simulates automation by running FTP in "unattended mode". You can get a better understanding by opening a command prompt and typing ftp /? .

[EDIT] I apologize, I missed your second question. Your script is only uploading the first file because it loops around the CreateTextFile method. This method is failing after the first attempt because the file already exists. What you really ought to do is loop around adding your files to the temporary file and then execute FTP only once. Your web server will appreciate the break as well.

Dim fso, folder, files, strPath
Set fso = CreateObject("Scripting.FileSystemObject")

strPath = "E:/Test"
Set folder = fso.GetFolder(strPath)
Set files = folder.Files

Const hostname = "ftp.domain.com"
Const port = 21
Const username = "username"
Const password = "password"
Const remoteDir =  "/"
Const useDefaultsExclusively = True
Const skipConfirmation = True

tempDir = shell.ExpandEnvironmentStrings("%TEMP%")
' temporary script file supplied to Windows FTP client
scriptFile = tempDir & "\" & fso.GetTempName
' temporary file to store standard output from Windows FTP client
outputFile = tempDir & "\" & fso.GetTempName

Set textFile = fso.CreateTextFile(scriptFile, True)

'input script
textFile.WriteLine("open " & hostname & " " & port)
textFile.WriteLine("user " & username)
textFile.WriteLine(password)
textFile.WriteLine("cd " & Chr(34) & remoteDir & Chr(34))
textFile.WriteLine("binary")
textFile.WriteLine("prompt n")

For Each item In files
    If InStr(1, item.Name, "txt") <> 0 Then
        textFile.WriteLine("put " & Chr(34) & item.Path & "\" & item.Name & Chr(34))
    End If
Next

textFile.WriteLine("quit")
textFile.Close

Set shell = CreateObject("WScript.Shell")
' bWaitOnReturn set to TRUE - indicating script should wait for the program
' to finish executing before continuing to the next statement
shell.Run "%comspec% /c FTP -n -s:" & scriptFile & " > " & outputFile, 0, True
WScript.Sleep 10
' open standard output temp file read only, failing if not present
Set textFile = fso.OpenTextFile(outputFile, 1, 0, -2)
results = textFile.ReadAll
textFile.Close

fso.DeleteFile(scriptFile)
fso.DeleteFile(outputFile)